Modeling the Contractile Event

Abstract

It is now well established that the myosin cross bridges are implicated in the contractile event and that it is likely that their attachment angle on the actin filaments varies during the cross-bridge cycle, thus producing tension. In this final chapter the attachment-detachment cycle of the cross bridges is considered in more detail, both in terms of the available mechanical data, of which only a brief summary will be given, and in terms of the various theories that have been proposed to account for it. Preliminary X-ray diffraction tests of these theories are then described and evaluated, as is the recent evidence on the time course of crossbridge movement during contraction. The chapter ends with a brief statement of the probable sequence of events that is involved in producing tension following a stimulus and also of the structural experiments that in the future are likely to be of most value in defining with more certainty the true nature of the contractile event.